Color photograph and process of making same.



PATENTED MAR. 29, 1904.

R. W. WOOD. COLOR PHOTOGRAPH AND PROCESS OF MAKING SAME.

APPLICATION FILED FEB. 14, 1899.

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Patented March'29, 1904.

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Application filed February 14, 1899.

To aZZ wit-oat may concern:

Be it kn that i, Eosnnr' N. Noon; 2. citidescribed herein of carrying my ion. depends on the principle that the .W uni produced by a diffractiongratmgz, combination with a lens which parallel co with re. or e vs of light are directed, is displaced ee to the direct image of the li ht sonrce oduced by the lens alone, and when viewed oy an eye placed in his spectrum the grating will appear illuminated with light of a color depending on the part of the spectrum in which the eye is placed. if in any part e grating the spacing between the lines he orierent, that portion will have a diderent color. since the spectrum formed by this portion is displaced relatively to the other, 3 and conseqoently light of a different color comes to the eye from this area of the grating. it a diffraction-grating he made up of patches in which the spacing between the lines is different, these patches will appear in colors depending the distance between the lines, and a colored picture can be produced by a proper distribution of these patches. as i shall presently point out.

The accompanying drawings will serve to make my invention more readily comprehended.

MADISON, /VlSCQNSllh PHQTQGRAPH fiiND FFEGGESS MAKlNQ SAME.

LGATION forming part of Letters Patent No. 55383, dated Eflarcfn 29, 198%.

Serial lilo. 705,490. (1:1 0 specimens.)

d is a front view or the difiractiongratng indicated in Fig. 2 the lens in. place. ig. 5 is a diagrammaticview of multicolored object to be photographed, the difiercolors e named on the drawing. Fig.

e 6 shows the cistribution of the grating-lines finished picture of the object shown in 5. *2 is a perspective view of a Vi wing constructed in accordance with my invention. 8 illustrates the manner in which the colored object is photographed throu h a screen. Fi 9 illustrates the manner which a sensitizing-plate may be printed with a diffraction-grating. Figs. 10., ii. and 12 show the manner in which the 6 finished colored photograph to he i successively printed with different diffraction-plates.

Like letters indicate like parts in the different views.

Figs. 1 and 2 are diagrams representing enses Z in combination with diffraction-gratngs g of uniform and varying gratingepace. t will be understood that the lines of the difmotion-grating are in reality microscopic and nvisible to the naked eye. The'image of the ight source is represented at c. The spectra or the colored rays resulting from the intertwo sets of lines of proper spacing, as shown in Fig. 2, two overlapping spectra will be formed, the red of one falling-0n the green of the other. and. an eye placed at this point receives red light from one part of the grating and green from another. Consequently the former appears red, the latter green. in any place these two spacings ove rlapthat is. 9 it both sets of lines are superimposed then the eye receives both red and green light from this portion. which consequently appears yeliow, since yellow is formed by a mixture of red and green lights. We can now imagine a third spacing to be present in some part of the grating. such that the clue of its spectrum falls on the spot where the red and green of the other two are superimposed; The eye will now see this latter area illuminated with blue light. If in any place all three spacings are presentthat is, if the three sets of lines are superimposed-then the eye Wlll receive red, green, and blue light from the portion,

which will appear white in consequence.

One way in which Ihave produced the .colored photographs is as follows: Three negatives, n, n, and n of the object 0, which may be diagrammatically illustrated by Fig. 5, are first taken with a camera 0 through red, green,

and blue screens 8', s and s in a usual manpositives in a manner as shown in Fig. 9, the

grating that is intended to give red light being impressed on the positive made from the negative taken through the red screen, the grating intended to give the green light being impressed on the positive made from the negative taken through the green screen and the grating intended to give the blue light being impressed upon the positive taken through the blue screen. A glass plate j, coatedwith bichromated gelatin or other suitable sensitizing material, is now exposed in succession under these three positives, as shown in Figs. 10, 11, and 12, proper registration being secured by the sides of a frame q or by marks on the plates, and on being washed with warm water or-otherwise developed this plate 1' becomes the finished colored photograph illustrated in Fig. 6.

A modification of the process just described, but not difiering in essential fundamental principles, is as follows: I provide the camera C with three screens d d and a? of red, green, and blue glass, on which the respective diffraction-gratings have been ruled or photographed. A sensitive plate p of fine grain is exposed under the three screens in succession. This plate when developed and viewed as I will describe appears as a colored positive, and to impress the colors on the eye of the observer I provide a viewing apparatus for combining the lens and the photograph and determining the directions from which the photograph is viewed. This viewing apparatus comprises a stand 0, supporting a cross piece or frame f, on the ends of which are mounted slides h and 71 for respectively supporting a lens Z and the associated colored positive jand the screen m. A source of light-as, for instance, an incandescent lightmay be placed a proper distance behind the positive j, which positive plate is located between the source of light and the lens Z. The screen m is made of opaque material, in which openings are provided to form eyeholes i i. I provide an adjustable connection k for regulating the angle of the arm on which the lens, photograph, and eyepiece are mounted, and the slidable mountings h and h allow regulationof the relative .positions of the lens and screen, as shown.

The lens is made of such focus that corresponding spectra formed on each side of the central uncolored image are at a distance apart equal to the distance between the eyes. As the eyeholes coincide with the superposed portions of the spectra, the color may be seen by both eyes at once. Slides n n are provided for altering the position of the eyeholes ii and for changing the distance betx I681! them. The yellows of the picture are produced by the mixture of red and green, and in those parts of the picture the two corresponding gratings are superposed. White is produced in all parts of the picture where all three of the gratings are impressed. A contact-print taken on a second glass plate coated withbichromated gelatin from the original color photographshows all the colors equally well and is! positive also.- Consequently copies can be inade in color as easily as blue prints, and

ofl, all being positive. I It will be observed that the effect of photographing an object through a colored screen is to produce a partial photograph of those portions of the object having the color of the screen, the parts or portions of the object having the color of the screen being selected and permitted to pass through the screen, while the other colors are substantially absorbed by the screen. It will also be observed that photographing with the gratings is to virtually photograph in various lights produced by such gratings. As a result it will be seen that in accordance with my invention 1 select out parts or portions of the object having different colors and photograph the same in correspondingly-colored.lights, the selection of the various parts or portions being done by the variously-colored screens and the photographing in the correspondingly-colored lights being due to the photographing through the mediufn of gratings. in the first one of the methods set forth herein the selection of the parts or portions having diflerent colors occurs first by the photographing of the object through different-colored screens upon separate negatives and the photographing of the difierent parts or portions in the correspondingly-colored lights is subsequently done by the subsequent photographing of the object upon the partial positives obtained from-such negatives through the various gratings after the positives have been sensitized. 1n the latter one of the two-methods the selecting oi the different portions or parts of the object having different colors and their photographing in the correspondingly-colored lights occurs simuitaneously, this being due to the fact that the photographing of the object through the vari- 90 from each one of these others can be struck ous gratings is done in connection with thevarious colored screens. In either case it will be seen the dilferent parts or portions of the object having different colors are selected and photographed in correspondingly colored lights.

While I have described in detail oneof the methods I follow in impressing a colored picture upon the eye of the observer, numerous modifications in the details of this process will suggest themselves to those skilled in the art.

y invention is not limited to this specific process which I have described.

I believe that it is broadly new with me to reproduce by photography the colors of the object photographed through the instrumentality of a diffraction-grating :of varying grating-space.

Having thus described my invention, what I claim as new, and desire to secure by Letters Patent, is

1. The method of producing a multicolored photograph which consists in photographing parts of an object having a given color, through a diffraction-grating adapted to produce the same color, substantially as described.

2. The method of producing a multicolored photograph which consists in superposing and registering monochrome photographs, eachtherewith, each adapted to produce a color corresponding to the color of the screen used therewith, and preparing a composite positive from the results of such photographic acts, substantially as set forth.

5. The method of producing a multicolored photograph which consists in successively photographing a multicolored object upon a sensitive element through a series of different colored screens and through a diffraction-grating associated with each of said screens, the color adapted to be produced by each diffraction-grating corresponding with the color of' its associated screen, substantially as set forth.

6. As an article of manufacture, a photograph consisting of a surface having areas of diffraction-rulings of different spacings, each spacing of diffraction-ruling being adapted to produce adifferent color, substantially as set forth.

7. As an article of manufacture, a photograph consisting of a surface having areas of superimposed difiraction-rulings of different spacings, each spacing of diffraction-ruling being. adapted to produce a different color, substantially as set forth. i

8. The method of producing a positive photograph, which consists in first taking separate 'negatives of the object to be photographed, through red, green and blue screens, from these negatives producing positives on glass, covering these positives with a sensitizing solution, photographing upon each positive a difi'raction-grating adapted to give its appropriate color, exposing a sensitized plate in succession under these positives, and finally developing this plate, substantially as described.

In witness whereof I hereunto subscribe my 7 name this 21st day of January, A. D. 1899.

' ROBT. W. WOOD.

Witnesses:

' CHARLES A. BROWN,

D. W. C. 'TANNER. 

